Favorinus? sp. 4
Order: NUDIBRANCHIA
Suborder: AEOLIDINA
Family: Glaucidae
PHOTO
UPPER RIGHT: Guam, Toguon Bay, 8 m; 14 May 1983. 4.5mm long.
LOWER PHOTOS: in egg mass of Atys multistriata Schepman, 1913. Length: 2.5 - 4mm. Guam, Toguon Bay, 8m; 14 May 1983.
PHOTOS: Clay Carlson.
One of a number of aeolid species which live and feed inside the opisthobranch egg masses they are feeding on. I have tentatively placed them all in the genus Favorinus, because of their general shape and their egg-eating habit.
See message below.
See also pages on Favorinus sp. 3 and Favorinus sp. 5.
Rudman, W.B., 2000 (July 18) Favorinus? sp. 4 [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/favosp4
Related messages
Photos of another egg-eating aeolid
August 11, 2000
From: Terry Gosliner
Dear Bill,
To accompany my photos of Denise's egg-eater, here are a couple of a second species, also from Madang, Papua New Guinea. Note that its egg ribbon has a double row of eggs, where the other species has a single row.
Best wishes,
Terry.
tgosline@CalAcademy.org
Gosliner, T., 2000 (Aug 11) Photos of another egg-eating aeolid. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/2847Thanks Terry,
This looks very like Clay Carlson's species with a white bar across each ceras.
Cheers,
Bill Rudman.
Egg-eating aeolids
July 22, 2000
From: C.Carlson & P.J.Hoff
Bill,
Here are some scans of one of the 4 or 5 'internal' egg eaters that we have. We have yet to find any on 'worm' egg masses though it is common to find both worm and cephalaspid, generally haminoeid, masses side by side on the sand. They can look almost identical. We think we can tell them apart by the nature of the attachment. The worm masses have a hole where they attach to the sand -- the haminoeids, none.
eo059x: 4.5mm; Guam, Toguon Bay, 8m; 14 May 1983. [food source unknown].
eo059e: in egg mass of Atys multistriata Schepman, 1913.
Length: 2.5 - 4mm. Guam, Toguon Bay, 8m; 14 May 1983.
We do have some observations of an eolid feeding on a non-opisthobranch egg mass though the situation was not natural. A number of years ago we went through 5 or 6 generations of another egg eater in our aquarium. We would find the juveniles and adults feeding on the eggs of Bittium
zebrum. The cerithids had been introduced earlier on a rock used as a
background for photography.
Clay & Patty Jo
clay.carlson@kuentos.guam.net
Dear Clay & Patty Jo,
Thanks for the information. I have put the photos of the second species you sent onto a separate page. It looks like the egg-eating species species Denise has just reported from Sulawesi may be feeding on haminoeid eggs rather than my suggested worm eggs. I thought I could identify the difference, which only goes to show it doesn't pay to be too confident.
The green and red ceratal digestive gland is interesting. I would have assumed that they would get the pigment from the eggs they feed on, but this is apparently not the case here. I guess it is possible they have been feeding elsewhere before they found this egg mass, but at this small size it seems unlikely. I will tentatively identify them as species of Favorinus.
Best wishes,
Bill
